1. Field of the Invention
The present invention relates to a photo-detecting module for use as an optical receiver in an optical transmission system.
2. Description of the Related Art
The photo-detecting module comprises such components as a photo-detecting device for converting received optical signals into electric signals, and an integrated circuit device having a pre-amplifier for extracting the electric signal from the photo-detecting device and the like. As shown in FIG. 1, a prior art photo-detecting module employs separate silicon substrates for the components. Referring to the figure, reference numeral 26 denotes a silicon substrate, 27 a photo-detecting device, 28 an integrated circuit device, and 29 bonding wires.
For this reason, when these components constitute a circuit-built-in module, separate rooms are required for respective components as shown in FIG. 1. In addition, in typical cases, bonding wires are used for connecting an optical segment to an integrated circuit device segment and for connecting the integrated circuit device to the package. The bonding wires are required to be equal to or more than 1 mm in length to provide a room for mounting, thus presenting a problem of inducing deterioration in high-frequency property.
An object of the present invention is to provide a photo-detecting module that allows the number of mounted parts to be reduced and the time for fabrication to be reduced by using the rear surface of a semiconductor integrated circuit device as a member for seating an optical fiber. Another object is to provide a photo-detecting module that is given an improved high-frequency property by flip-chip mounting a semiconductor integrated circuit device via solder bumps and thus eliminating the need for respective connections to the photo-detecting device using bonding wires.
The photo-detecting module according to the present invention comprises a module substrate on which a wiring pattern is formed. An integrated circuit device is mounted on said module substrate via solder bumps so that the front surface thereof where an integrated circuit is provided faces said module substrate. Said integrated circuit device has a groove on the rear surface thereof. An optical fiber is seated within said groove formed on the rear surface of said integrated circuit device. A photo-detecting device is mounted on said module substrate for receiving light transmitted through said optical fiber.
Said integrated circuit device and photo-detecting device may be mounted on a block that is used for positioning those in the direction of height.
Furthermore, said groove may be formed in the shape of letter V. Also, an optical fiber retainer may hold said optical fiber by sandwiching said optical fiber with said integrated circuit device.
According to the present invention, the optical fiber is seated within an optical fiber seat groove provided on the integrated circuit device, and the semiconductor integrated circuit device is flip-chip mounted on the module substrate via solder bumps. Moreover, the photo-detecting device and the semiconductor integrated circuit device are connected to each other by means of a wiring pattern provided on the module substrate. Such use of the rear surface of the semiconductor integrated circuit device as an optical fiber seat member allows the number of mounted parts to be reduced and the time for fabrication to be reduced. In addition, flip-chip mounting of the semiconductor integrated circuit device via solder bumps eliminates the need for respective connections to the photo-detecting device using bonding wires, thus also enabling providing an improved high-frequency property.